JPH02235627A - Substrate for high frequency circuit - Google Patents

Abstract

PURPOSE:To obtain a substrate having high specific inductive capacity epsilonr, reduced in the irregularity thereof and low dielectric loss tangent tanepsilon by superposing a required number of resin sheets containing a fine particulate dielectric having high specific inductive capacity epsilonr and low dielectric loss tangent tandelta and further laminating a resin impregnated base material and/or a resin layer between the resin sheets or the outermost layer of said resin sheet if necessary to form a dielectric layer and laminating a metal conductor layer to at least one surface of said dielectric layer. CONSTITUTION:Metal conductor layers 1, 1', resin sheets 2, 2' and fine particulate dielectrics 3, 3' have high specific inductive capacity(high epsilonr) and low dielectric loss tangent(low tandelta) and, if necessary, a resin impregnated base material 4 and resin layers 5, 5' are used. These materials can employ arbitrary constitution wherein a large number of said materials are laminated if necessary and can be also formed into a multilayer plate. As the resin forming the resin sheets 2, 2', a polyolefin resin such as polyethylene is pref. The fine particulate dielectrics 3, 3' are ones having epsilonr higher than that of the resin sheets and tandelta lower than 0.05(1MHz) and an average particle size of 300mum or less and titanium dioxide ceramic is pref. As the metal conductor layers 1, 1', a copper foil for a printed circuit is pref. The resin impregnated base material is used in order to hold dimensional stability and mechanical strength and formed by melting a film of a thermoplastic resin film on cloth composed of a synthetic fiber under heating and pressing the same to impregnate the cloth with said resin. The resin layers 5, 5' are used in order to secure the bonding strength between the metal conductor layers and the resin impregnated base material or resin sheets.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a substrate for electronic equipment, particularly a high frequency circuit substrate suitable for use in a high frequency region. (Prior art) In recent years, in the fields of electronics and communications industries, the frequencies used have gradually shifted to the high frequency range, and the importance has shifted from the kilohertz range, which had traditionally been widely used, to the megahertz and gigahertz ranges. It is transitioning. In the high frequency region, the relative permittivity is low. Although a substrate with a low dielectric loss tangent is used, it has the disadvantage that the circuit cannot be made smaller due to its small relative dielectric constant (hereinafter abbreviated as εr). For this purpose, for example, as shown in JP-A No. 61-285230, Bripreg, which is a glass cloth impregnated with a fluororesin containing barium titanate, is used;
As shown in Japanese Patent No. 19451, a method has been proposed in which barium titanate is adhered to glass cloth and a blob leg impregnated with fluororesin is used to improve tr and downsize the circuit. When adopting these methods,
Inside the board! In order to reduce the variation in r, barium titanate must be uniformly contained between the weaves of the glass cloth or uniformly adhered to the surface of the glass cloth. It is difficult to crush small enough to penetrate between the weaves, and can fall off if attached to a glass cloth surface. Therefore, although these methods can improve 6r, they have the drawback of increasing the variation in εr within the substrate. In addition, in high-frequency circuit boards, dielectric loss tangent (hereinafter ta) is used to reduce signal attenuation.
(abbreviated as nδ) needs to be low, but since the substrate manufactured by the method described above is mainly composed of glass cloth, tanδ must be low.
It also had the disadvantage of being high. (Problems to be Solved by the Invention) The present invention has been made in view of the above circumstances, and has a high gf, a small variation thereof, and a tan δ
This provides a substrate for high frequency circuits with low energy consumption. (Means for Solving the Problems) The present invention consists of stacking a required number of resin sheets containing a dielectric material in the form of fine particles with high εr and low tanδ, and further impregnating resin between the resin sheets and the outermost layer as necessary. base material and/or
Alternatively, the present invention provides a high frequency circuit board characterized in that a resin layer is laminated and a metal conductor layer is laminated on at least one surface of the dielectric layer.

The present invention will be explained in detail below with reference to the drawings. FIG. 1 is a cross-sectional view showing the laminated structure of the present invention, where 1.1' is a metal conductor layer, 2.2' is a resin sheet, and 3.3' is a fine particle dielectric material with high gf and low tanδ. If necessary, a base material impregnated with resin No. 4 and a resin layer No. 5.5' may be used. Each of these constituent materials can have an arbitrary structure in which a large number of them are laminated according to the need, and can also be made into a multilayer board.

In the present invention, resins forming the resin sheet 2.2' include homopolymers such as polyethylene, polypropylene, poly-1-butene, and poly-4-methyl-1-pentene, ethylene-brobylene copolymers, Polyolefin resins such as polyolefin copolymers such as ethylene-1-butene copolymer, brobylene-1-butene copolymer, and ethylene-vinyl acetate copolymer, volite 1-fluoroethylene, tetrafluoroethylene-hexafluoro Fluorine resins such as brobylene copolymer, tetrafluoroethylene-perfluoroalkoxyethylene copolymer, trifluorochloroethylene-tetrafluoroethylene copolymer, polyvinylidene fluoride, polyfluorinated vinyl, polystyrene, acrylic nitrile Styrene copolymer, acrylonitriloptadiene-styrene copolymer, polycarbonate, various polyacrylates such as polymethyl methacrylate, polyvinyl butyral, polyvinyl formal, polyimide, polyamide, polyamideimide, polyphenylene sulfide, polyether sulfone, polysulfone, Polyarylate, polyetheretherketone, polyphenylene oxide, polyetheramide, polyetherimide polyisobutylene, polyoxybenzylene, polybutylene terephthalate, polybutadiene, polyester, polyvinyl chloride, polyvinylidene chloride, urea resin, melamine resin, penzoguanami resin,
Examples include diallyl phthalate resin, polyisocyanate resin, and phenoxo resin, and these may be modified as appropriate.8Also, a mixture or copolymer of these may be used as a composite, and these may be used as the main components, and a crosslinking agent may be added if necessary. , curing agents and additives may also be used. Among these,
Polyolefin resins such as polyethylene, polypropylene, polytetrafluoroethylene, and fluorine resins are preferred, and polyolefin resins are more preferred from the viewpoint of moldability and cost.

3,3' high εr, low tan δ fine particle dielectric material has εr higher than that of the resin sheet and tan δ of 0.05.
(lMHz) is a dielectric material with an average particle size of 300 μm or less, including aluminum oxide, titanium dioxide ceramic, barium titanate ceramic, lead titanate ceramic, strontium titanate ceramic, calcium titanate ceramic, titanium At least l° of ceramics selected from the group consisting of bismuth oxide ceramics and magnesium titanate ceramics, or at least two of the above ceramics are mixed, and if necessary, unozymium oxide, samarium oxide, and oxidized Added lanthanum, cerium oxide, etc., fired and crushed, or glass fiber, glass chips, Kg O-PbO
Siot glass or the like can be used. Among these, titanium dioxide-based ceramics and barium titanate-based ceramics are preferred, and barium titanate-based ceramics are more preferred because of their high ε'. Particle size is 0.0
A thickness of about 15 to 100 μm is desirable from the viewpoint of dispersibility. The amount of ceramic to be added to the resin can be varied depending on the required dielectric constant, etc., but it is preferably 30 to 400 parts by weight (hereinafter referred to as parts) per 100 parts by weight of the resin. That is, if it is less than 30 parts, sr is difficult to increase, and if it exceeds 400 parts, moldability during molding tends to decrease. The metal conductor layer 1.1' is a foil or plate of copper, cupronickel, bronze, brass, aluminum, nickel, iron, stainless steel, gold, silver, platinum, or the like. As the metal conductor layer, copper foil for printed circuits is generally preferred, and among copper foils, extremely high-purity oxygen-free W4 foil is preferred. Also, instead of metal foil or plate, copper plating, silver plating, etc. may be used to form a predetermined circuit. Resin-impregnated base material 4
For example, it is used to maintain dimensional stability and mechanical strength, and is made by impregnating synthetic fiber, glass fiber, etc. cloth or paper with thermoplastic resin film or the aforementioned plastic by heating, melting, and pressurizing. It is possible to use a material that has been dissolved and impregnated with a volatile solvent. The resin-impregnated base material is for reinforcing the dielectric layer and has a thickness of 2
A material obtained by melt-impregnating a 20-200 μm thermoplastic resin sheet into a 0-500 μm glass cloth is preferably used. In addition, in order to eliminate the increase in tan δ due to the base material and maintain dimensional stability and mechanical strength, one of the metal conductor layers 1 and 1' should have a thickness of at least 0.1 mm without using a resin-impregnated base material.
A metal plate with a diameter of mm or more may be used. The resin layer 5.5' is used to ensure adhesive strength between the metal conductor layer and the resin-impregnated base material or resin sheet, and is preferably made of a plastic film or adhesive resin. (Function) The high frequency circuit board of the present invention has a resin sheet with high ε',
Since the structure contains a particulate dielectric material with a low tan δ, it is possible to uniformly disperse the dielectric material compared to a structure in which a particulate dielectric material with a high Sr and low Lan δ is contained in a base material such as glass cloth. It is easy and it is possible to reduce the variation in tf within the substrate. Furthermore, it is possible to reduce or eliminate the amount of a base material with a high tan δ used, and the tan δ of the substrate can be lowered. (Examples) Hereinafter, the present invention will be explained in detail based on Examples, but the present invention is not limited thereto. Example High-density polyethylene powder (Hizefukus Powder-62
008P, melting point 132℃, Mitsui Petrochemical Industries ■Product name)
100 parts of barium titanate ceramic NPO (average particle size 5 μm, trade name of Fuji Titanium Industries Co., Ltd.) powder 150 as a fine particle dielectric with high εr and low Lan δ
After melting and kneading with a roll at 150°C, the resin sheet containing the dielectric with a high C' and a thickness of 0.5 mm was obtained by molding with a press at 150°C. As the resin-impregnated base material 4, a 50 μm thick Admer film (polyolefin adhesive film, Mitsui Petrochemical Co., Ltd. trade name) was layered on a 60 μm thick glass cloth (manufactured by Nittobo Co., Ltd.) at 150°C. After heating and melting, pressure was applied to obtain a resin-impregnated base material. Using 35 μm copper foil (manufactured by Nippon Mining Co., Ltd.) as the metal conductor layers 1 and 1', and using 50 μm thick Admer film (trade name of Mitsui Petrochemical Industries Ltd.) for the resin layers 5 and 5', the first These were laminated in the configuration shown in the figure, and heated and bonded using a spacer at 110° C. to obtain a high-frequency circuit board with a substrate thickness of 1.2 mm. Comparative Example 1 The same polyolefin resin powder as in the example was dispersed and dissolved in xylene at 120°C to make a 30% solution, and the same barium titanate ceramic powder as in the example was mixed with 1.5 times the resin. The weight was added to 7.

While keeping the solution warm and stirring, the same glass cloth as in the example was impregnated with the resin and ceramic powder, and dried to remove xylene to obtain a blibreg. 6 the pre-leg
The sheets were stacked, heated and melted using a press at 150°C, and then pressed to obtain a resin-impregnated base material containing ceramic powder.The same copper foil and resin layer as in the example were made into a structure as shown in Figure 2.
A high frequency circuit board with a substrate thickness of l, 2 mm was obtained by heat bonding in the same manner as in the example. Comparative Example 2 A high-frequency circuit board having a thickness of 1.2 mm was obtained in exactly the same manner as in Comparative Example 1, except that the ceramic powder was not used.

Table 1 shows the εr and tanδ of each of the high frequency circuit boards produced in Example, Comparative Example 1, and Comparative Example 2. Table Example and Comparative Example 1 were able to increase εr by containing fine particle dielectric material with high εr and low tan δ, but Comparative Example 1 had a large glass cloth fraction, so t
anδ is large. Further, in Comparative Example 1, a variation of 6r occurred. On the other hand, in the example, the value of εr is uniform,
Tanδ was also a small value. (Effects of the invention) According to the present invention, the high tr, low tan δ fine particle dielectric material contained in the resin sheet makes it possible to increase εr with little variation, reducing the amount of base material used. This makes it possible to keep tan δ low.This makes it possible to downsize the circuit formed on the substrate and to keep signal attenuation low.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a high-frequency circuit board according to the present invention, and FIG. 2 is a cross-sectional view of a high-frequency circuit board obtained in a comparative example. Explanation of symbols 1.1' Metal conductor layer 2, 2' Resin sheet 3.3' Particulate dielectric material 4 Resin-impregnated base material 5.5' Resin layer Fig. 2

Claims (3)

[Claims] 1. A required number of resin sheets containing fine-particle dielectric material with a high dielectric constant and a low dielectric loss tangent are stacked, and if necessary, a resin-impregnated base material and/or a resin layer are laminated between the resin sheets and on the outermost layer. 1. A high-frequency circuit board comprising a dielectric layer and a metal conductor layer laminated on at least one surface of the dielectric layer. 2. The high frequency circuit board according to claim 1, wherein the resin is a polyolefin resin. 3. 2. The high frequency circuit board according to claim 1, wherein the particulate dielectric material having a high dielectric constant and a low dielectric loss tangent is barium titanate ceramic powder.